Found it! An accurate address (at least according to Google) is 34 Voight Dr, Deadwood, SD. Today, a subdivision sits on the property with no trace of the drive-in remaining.
http://tinyurl.com/jnb6zvn

The Mile-Hi Drive-In Theatre launched with “Branded” on May 27, 1955. In 1958, “North by Northwest” with its climactic Black Hill scene proved popular with locals and tourists. The theatre closed for the season September 24, 1978 with “The Norseman” and did not re-open. It was razed